WO2022139620A1

WO2022139620A1 - Printing head and printing method

Info

Publication number: WO2022139620A1
Application number: PCT/RU2020/000754
Authority: WO
Inventors: Артем Владимирович БАРАХТИН; Константин Юрьевич СОЛОВЬЕВ; Александр Васильевич МАЛОЛЕТОВ; Александр Сергеевич КЛИМЧИК
Original assignee: Общество с ограниченной ответственностью "АРКОДИМ"
Priority date: 2020-12-25
Filing date: 2020-12-25
Publication date: 2022-06-30

Abstract

The invention relates to the field of 3D printing, and more particularly to the structure of a printing head for construction 3D printers for printing buildings, structures, hardscape elements and the like from mortar, and to a printing method using said 3D printer. The present printing head comprises a load-bearing frame, a mortar mixing device, a printing assembly, and a pump for supplying prepared mortar to said printing assembly, wherein the printing assembly comprises at least one reservoir and a dispensing module disposed below said reservoir and having a plurality of dispensing openings, the dispensing module being configured to allow the extrusion of mortar through several openings simultaneously in one pass of the printing assembly. The technical result consists in increasing the efficiency of building operations; increasing the strength of the buildings and structures produced; reducing the inertial loads on and the mass of the construction printer structure, as well as the installed capacity of the printer; making it possible to print complex geometric forms having different profiles and sizes; and reducing the complexity of the printing head control algorithms, as well as reducing vibrations linked to a change in direction of the printing head.

Description

PRINT HEAD AND PRINT METHOD

Technical field

The invention relates to the field of 3D printing, in particular to the design of the print head of building 3D printers for printing buildings, structures, small architectural forms, etc. from mortar and a method for printing on a 3D printer.

Prior Art

Three-dimensional printing (3D printing) is the production of objects by layering material with a print head, nozzle, or other printing technology.

Devices are known in which the printing method is carried out by extrusion of mortar through one or more nozzles of a fixed section, and the extrusion process is controlled only by controlling the mortar supply rate or by shutting off the supply of mortar when the valve is closed (RF patent for utility model No. 179153, IPC E04G 21/16, B41J 2/335, published 04/28/2018; RF utility model patent No. 191900, IPC B29C 64/209, B41F 17/00, published 08/28/2019) change in direction of its movement. For printing walls or other wide structural elements, printing is implemented in several passes.

The disadvantage of these devices and the method of applying the mortar is the need to print lines of a fixed width and, as a consequence of this: the impossibility of printing structural elements of continuously adjustable width and the associated restrictions on possible architectural solutions; the need for fast movements and numerous changes in the direction of movement of the print unit when printing curly lines and the associated increased inertial loads on the design of the 3D printer, which in turn leads to unwanted vibrations, the need to use more complex algorithms for controlling the extruder head and increased wear on mechanical components control mechanical system; reduced strength properties in places of lateral connection of material lines; the need to print the walls of buildings or other wide elements in several passes and the associated low

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SUBSTITUTE SHEET (RULE 26) the productivity of construction work, which affects the strength of the bonds between the layers of the walls; inability to print components with sharp corner components; the impossibility of printing components of a smaller width than the radius of the extruder nozzle.

Known print head inkjet 3D printer (RF patent for utility model No. 161249, IPC B41J 2/00, published 04/10/2016), containing a movable platform made in a single housing with two nozzles with heaters placed on it and a nozzle switching mechanism, the position of which is determined position sensor of the movable platform and is limited by a position limiter, while the print head of the inkjet 3D printer is equipped with a valve for nozzles, made with the possibility of deflection, which ensures that one of the nozzles is locked and the other is opened when switching nozzles, while the nozzles are made movable relative to the valve, which is made motionless.

The specified technical solution does not allow printing products of complex geometry or several components in one pass. The given solution is unsuitable for printing with concrete-cement mixtures due to printing features and process requirements.

Known printhead with movable needles (RF patent No. 2701996, IPC B29C 64/00, B29C 64/112, B29C 64/20, published 02.10.2019), which contains an opening through which the material is squeezed out, a chamber for containing the ejected material, a channel , connecting the chamber to the hole, and a movable needle that enters the hole and squeezes the material out of the hole. The print head is configured to extrude material with a viscosity of 10,000 centipoise (cP) (Pa-s) or more at an elevated temperature.

The proposed technical solution does not allow you to adjust the width of the printed lines - the holes are fixed in width and allow extrusion of the material only of the appropriate width. In addition, the holes are spaced apart (there are significant distances between them), which means that there are no connections between the individual lines that are printed from individual holes. It is possible to ensure the connection of print lines with a rather complex control of the longitudinal-transverse movements of the entire head as a whole, which will give negative effects associated with large inertial loads, deterioration in the quality of the surface of the printed object and an increase in 2

SUBSTITUTE SHEET (RULE 26) time to print. However, even if the lines are connected in this way, the lines will overlap, which is unacceptable for the tasks of construction 3D printing. Also, for printing curved walls, it will be necessary to ensure the appropriate rotation of the entire extruder head as a whole in the range of angles of at least -180 to +180 degrees, which will lead to the need to suspend the printing process in the corner joints of the walls when changing the direction of movement or when reaching restrictions on maximum angles turn.

Known printhead for building 3D printers (RF patent for utility model No. 198857, IPC E04G 21/16, B33Y 30/00, B41J 2/335, published on 07/30/2020), which contains a monoblock body made of metal, metal alloy or a composite material with the required strength, inside which there is a container for the building mixture, equipped with a dosing screw, also contains extruders connected by flexible hoses to the container for the building mixture and equipped with a movement and positioning mechanism and a device for preparing and supplying the mixture to the print head, characterized in that that a rail with a gear train is rigidly fixed on the monoblock body, to which four extruders are attached through the movement and positioning mechanism, and a cartridge for all-metal expanded metal mesh, a feeder for all-metal expanded metal mesh, and cutting shears are rigidly fixed on the monoblock body all-metal expanded metal mesh and ro face positioning all-metal expanded metal mesh.

The solution given in the mentioned patent allows using only a strictly defined number of nozzles (four), the fixed sizes of which do not allow adjusting the width of the print lines.

The above solution does not allow changing the direction of movement of the print head at the corner points of the structure. That is, to print curved walls (including both smooth changes in wall curvature and printing of corner elements), the mechanism of the ZP printer will need to provide appropriate rotations of the entire extruder head as a whole, and ensure these rotations are consistent with the operation of other mechanisms in a range of angles of at least from -180 to +180 degrees. This will also lead to the need to pause the printing process in wall corner joints when changing direction of movement or when limits on maximum rotation angles are reached.

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SUBSTITUTE SHEET (RULE 26) Placing the nozzles on the same guide does not allow printing lines without gaps between them - that is, the lines of the material will not connect to each other and the integrity of the structure will be violated. The patent does not disclose how the nozzles will be driven along the rail, but it is obvious that independent control of the nozzles will require the use of independent drives that must move along with the nozzles on the rail, which greatly complicates and makes the design heavier, increasing inertial loads. The flexible hoses must be long enough to allow the nozzles to move freely, which means they will sag when they enter the print area. Constant cycling of hoses can also lead to rapid wear.

The proposed solution does not allow modifying the mixture on the extruder by adding dyes and additives, which does not allow controlling the setting of the solution and, if necessary, speeding up or slowing down the process of setting the building mixture.

As the closest analogue, a 3D print head was selected (patent EP3427930, IPC B29C 67/00, published on May 09, 2017), which includes an inlet pipe equipped with a hole; a shutter located in the hole and made with the possibility of sliding, where the hole includes an open and closed area of the shutter; and the area not covered by the shutter forms the outlet port 3 of the D print head. The outlet includes a first end and a second end defining the length of the outlet. The drive device receives a control command from the control device and drives the shutter. By adjusting the position of the first end and/or the position of the second end in the hole, the length of the outlet is determined.

The proposed solution contains one or more slotted holes spaced apart in space, therefore, to print curved walls, it will be necessary to provide appropriate rotations of the entire extruder head as a whole in the range of angles of at least -90 to +90 degrees. This means the need to pause the printing process at wall corners, when changing direction, or when limits on maximum rotation angles are reached. In addition, spaced slot holes do not allow the formation of a common slot of a complex shape, which, on the one hand, limits the possibility of printing complex profiles, and, on the other hand, creates the risk of overlapping lines from adjacent slots, the elimination of which complicates the control of the print head.

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SUBSTITUTE SHEET (RULE 26) The proposed solution is designed to operate the printer using FDM technology, in particular, it provides the pressure necessary for extrusion of the material by supplying a plastic thread, and cannot be used for printing with mortar due to the lack of devices that provide mixing and supply of the mortar. The proposed solution also does not imply the possibility of adjusting the composition of the material during the printing process.

Disclosure of invention

The technical objective of the invention is to develop a print head for a construction printer and a printing method using the specified print head to ensure the extrusion of mortar simultaneously in several lines through adjustable holes.

The technical result is to increase the productivity of construction work; increasing the strength of buildings and structures under construction; reduction of inertial loads, weight of construction printer construction and its installed power; providing the ability to print complex geometric shapes of various profiles and sizes; reducing the complexity of print head control algorithms and oscillations associated with a change in the direction of movement of the print head.

The technical result is achieved by the fact that the print head includes a carrier frame, a mortar mixing device, a printing unit, a pump for supplying ready-made mortar to the print unit and a drive for moving the entire print head, while the print unit contains at least one reservoir and a dispensing module located under the reservoir and containing a plurality of dispensing holes, configured to extrude the mortar simultaneously through several holes in one pass of the printing unit.

Brief description of the drawings

The invention is illustrated by the following drawings:

Fig.1 - Scheme of printing when implementing the print node in the form of movable shutters,

Fig.2 - Scheme of printing when implementing the print unit in the form of movable carriages with nozzles,

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SUBSTITUTE SHEET (RULE 26) Fig.Z - Scheme of printing when implementing the print unit in the form of a spunbond board.

Embodiments of the invention

The printhead is intended for use as part of a construction 3D printer based on a handling device to ensure the extrusion of the mortar in several lines simultaneously through adjustable holes. As part of such a 3D printer, both one and several print heads can be used. The print head can be mounted on various types of handling devices such as cable robots, industrial robots, movable chassis, mobile robots, and the like. The method of installing the print head on the manipulation device is determined by the design features of this device. So, for installation on an industrial robot, standard fasteners must be provided on the print head. To attach to a rope robot, eyelets for attaching ropes must be provided. Thus, the movement of the print head as a whole in the working area 3 of the D printer is provided by the movement of the mechanism of the 30 printer.

The print head contains a carrier frame on which a mortar mixing device, a printing unit and a pump for supplying the finished mortar to the printing unit are installed.

The carrier frame is a structure made of metal or composite materials to which all other elements of the print head are attached. In one embodiment, the self-supporting housing of one or more printhead elements performs the function of the carrier frame. It is also possible to combine a self-supporting housing of one or more elements of the print head and a carrier frame for attaching the remaining elements.

The mortar mixing device contains a continuous mixer, for example, a forced mixer or a combined mixer (gravity-forced), at least two pipes for connecting hoses for supplying building material components, as well as valves for controlling the supply of each of the building material components.

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SUBSTITUTE SHEET (RULE 26) The supply of building material components to the print head is carried out through sleeves that are attached to the nozzles. Branch pipes through valves join the mixer. Thus, the incoming components of the building material (for example, water, dry building mix and modifying additive) enter through the sleeves, pass through pipes, valves and enter the mixer. In the mixer, the components are mixed to prepare the finished mortar. After that, with the help of a pump, the finished mortar is fed to the printing unit.

The pump for supplying ready-made mortar to the printing unit is a positive displacement pump, such as gerotor, rotary vane, peristaltic, etc. The pump is driven by a variable speed drive, such as a servo motor, variable frequency asynchronous motor, stepper motor, etc., if necessary, the drive also includes a gearbox.

The printhead printing unit includes a dispensing module and at least one reservoir from which the finished mortar is supplied to the dispensing module. In this case, the mortar enters the tank through the inlet pipe using a pump.

The tank can be made with a wide slot 1 (Fig.1), with nozzles for connecting flexible hoses, or in the form of a container with an open bottom. The issuing module can be made in the form of movable elements 2 (2a, 26, Fig.1, Fig.2) or spunbond board 3, acting as the bottom of the tank (Fig.3).

Movable elements 2 can be made in the form of at least one pair of separate shutters 2a (Fig.1), a single shutter with a window or a movable carriage with a nozzle 5 moving along the guide 26 (Fig.2).

When the moving elements are made in the form of a pair of individual curtains 2a, the mortar from the tank is supplied through the slot 1, made above the movable curtains 2a, and then squeezed out through the windows 4 formed when the individual curtains 2a are extended (or through the fixed windows when using a solid curtain). By controlling the movement of individual shutters 2a, it is possible to adjust the position and width of windows 4, while individual windows can be completely covered. When using one-piece shutters, only the position of the windows can be adjusted, which can be moved beyond the slot 1 made above the movable shutters.

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SUBSTITUTE SHEET (RULE 26) In the case of performing movable elements in the form of carriages with nozzles 5, the carriages move along the guides 26, ensuring at each moment the required position of the nozzles 5 relative to the print head. Nozzles 5 are equipped with controlled valves that allow opening and closing of individual holes in accordance with the printing program. The mortar comes from the tank through flexible hoses to nozzles 5, which ensure its issuance when the corresponding valve is opened. If the valve is closed, the mortar will not be extruded through the corresponding nozzle. Thus, at any time, part of the valves can be closed in accordance with the print program, and only the nozzles, the valves of which are open, ensure the release of the material.

Each movable element 2 (curtain 2a or carriage 26) moves along its guide using an individual linear movement drive based on servomotors, stepper motors and similar motors.

When the dispensing module is made in the form of a spunbond board 3 (FIG. 3), the holes of the spunbond board 6 are arranged in the form of a matrix and are also provided with controlled valves that allow closing and opening individual holes in accordance with the printing program. In a particular case of implementation, the valves are triangular, square, rectangular, hexagonal, or other shapes, located close to each other without gaps and close the holes of the corresponding shape. At the same time, in one of the embodiments, the centers of the holes in the rows are displaced relative to the adjacent row, thereby providing a denser filling of the area of the spunbond board. In addition, the holes may not occupy the entire area of the spunbond board, but be located at least in one row, diagonally, along concentric circles and other lines. The spunbond board can be integral with the tank and thus represent its bottom. Thus, in the tank directly above the die plate there is a mortar, which, under the pressure created by the pump, is squeezed out through the holes of the die plate when the valves are opened.

In all possible versions of the design, the technical goal of the invention is achieved by extruding the mortar through several holes simultaneously, resulting in a monolithic structure 7, created in one pass of the printing unit.

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SUBSTITUTE SHEET (RULE 26) The printing unit can be equipped with a system for supplying and mixing additives and dye pigments.

The volumes of the solution supplied to the printing unit and consumed in the printing unit must be strictly coordinated. To prevent accidents in the event of a mismatch between the pump wires and moving parts, the printing unit includes a safety valve that allows you to direct excess mortar back to the pump suction pipe (or mixer) or discard the excess as waste. The operation of the safety valve is a signal to stop printing and carry out repair or cleaning work.

The printhead can be equipped with auxiliary components that provide a given vertical print profile (smooth or specially shaped). Auxiliary components are mechanical forming elements in the form of flat or curved plates, spatulas, scrapers, etc., which form the surface of the printed object and can be used to create a vertical profile with a complex horizontal profile.

Principle of operation:

Mortar extrusion is carried out simultaneously in several lines through adjustable holes.

The print head is attached to a handling device that provides the required movement of the print head in the working area.

The supply of mortar components to the print head is carried out through hoses from appropriate stationary installations, for example, an air pump for supplying a dry mixture, a water pump for supplying water, etc. In a particular case, when making movable elements in the form of curtains, one or more components are located in a special reservoir as part of the print head and are supplied by an appropriate pump.

The components of the building material enter the mixer through nozzles. The supply of components is programmatically controlled using controlled valves, ensuring the supply of the required amount of each component at any given time, depending on the software-set requirements for the finished solution and taking into account the parameters

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SUBSTITUTE SHEET (RULE 26) environment (air temperature, air humidity) and the actual consumption of the finished mortar.

The mixer prepares the ready-made solution, which is continuously fed into the tank of the printing unit with the help of a pump. The volume of the supplied solution is programmatically regulated in accordance with the planned flow rate at each moment of time.

Next, the mortar is supplied from the tank either through the slot 1 and then squeezed out through the windows 4, formed by moving apart the individual curtains 2a, or through the fixed windows in the solid curtains; or the mortar is supplied from the tank through flexible hoses through nozzles 5 mounted on carriages moving along guides 26; or through the holes 6 of the spunbond board 3. The shape of the spunbond board opening can be round, square, rectangular, hexagonal or other shape.

By coordinating the movement of the shutters 2a, the opening/closing of nozzles 5 or holes 6 using valves, and the movement of the entire print head using the mechanism of the ZP printer, it is possible to ensure continuous extrusion of the building material in several lines. This ensures the printing of an arbitrary number of arbitrarily complex lines (within the capabilities of a specific head design) up to the complete filling of the entire print width with material in one pass of the print head with a multiple reduction in inertial loads compared to known analogues.

The use of the die board 3 allows printing lines in an arbitrary direction without turning the printing unit.

The version with die board 3 simplifies and speeds up the printing of individual monolithic elements, such as columns, corner joints, reinforced elements in window and door openings, etc.

This provides an adjustable width of the printing area and the required profile of the building wall or structure element. If necessary, printing is possible when the printing unit moves in the lateral direction. It is possible to change the print direction without turning the print head by changing the print profile. To change the printing direction (for example, when printing curved walls, the change occurs gradually over time, and when printing the corners of a building, the direction change occurs “instantly”), it is not necessary to turn the entire print head, unlike known solutions. Changing the print direction

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SUBSTITUTE SHEET (RULE 26) provided by the translational movement of the head in the desired direction and the appropriate control of the opening or closing of the valves or adjusting the position and size of the slots.

Bulk, liquid, viscous and other types of materials can be used for printing with the inventive printhead, including:

• use of both one material and several materials at the same time, organizing their extrusion through different nozzles;

• the use of both single-component and multi-component mixtures, ensuring their mixing directly on the print head;

• use with building mixtures based on various binders (gypsum, cement) and special additives that provide programmable material properties controlled during printing;

• changing the consistency of the building mix can be carried out during the printing process by mixing water on the print head.

In the event of a significant mismatch between the operation of the pump wires and the curtains, the safety valve is activated, after which it is necessary to stop printing and, if necessary, carry out repair or cleaning work.

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Claims

Claim

1. A print head including a carrier frame, a mortar mixing device, a print unit, a pump for supplying ready-made mortar to the print unit, the print unit comprising at least one reservoir and an issuing module located under the reservoir and containing a plurality of dispensing holes, made with the possibility of squeezing out the mortar simultaneously through several holes in one pass of the printing unit.

2. The print head according to claim 1, characterized in that the output module is made in the form of movable elements.

3. The print head according to claim 2, characterized in that the movable elements are made in the form of at least one pair of separate shutters.

4. The print head according to claim 2, characterized in that the movable elements are made in the form of at least one integral shutter with a window.

5. The print head according to claim 2, characterized in that the movable elements are made in the form of at least one carriage with a nozzle.

6. The print head according to claim 5, characterized in that the nozzles are equipped with controlled valves that open and close individual holes in accordance with the print program.

7. The print head according to claim 1, characterized in that the dispenser module is made in the form of a spunbond board.

8. The print head according to claim 7, characterized in that the holes of the die plate are arranged in at least one row in the form of a matrix.

9. The print head according to claim 8, characterized in that the holes of the die board are located diagonally, along concentric circles or other lines.

10. The print head according to claim 8, characterized in that the centers of the holes of the die board in the rows are offset relative to the adjacent row.

I. The print head according to claim 8, characterized in that the shape of the hole of the die board is round, triangular, square, rectangular, hexagonal or other shape.

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12. The printhead according to claim 8, characterized in that the openings of the die board are formed by opening valves of a square, rectangular, hexagonal, triangular or other shape, located close to each other without gaps.

13. The print head according to claim 8, characterized in that the holes of the die board are equipped with controlled valves that close and open individual holes in accordance with the printing program.

14. The print head according to claim 1, characterized in that the print head is equipped with auxiliary components that provide a given vertical print profile. 15. The print head according to claim 1, characterized in that the printing unit is equipped with a system for supplying and mixing additives and coloring pigments.

16. The print head according to claim 1, characterized in that it contains at least one safety valve that is activated when the pump wires and shutters do not work correctly.

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